The overall goal of the research being conducted is to identify the activities and interrelationships of epithelial cells, mesenchymal cells and extracellular matrix which are responsible for palatal shelf reorientation. During the next year we plan to complete an analysis of hyaluronate distribution in the anterior, posterior and soft palatal shelf regions during the course of in vivo and in vitro palatal closure in normal and chlorcyclizine-treated embryos. Computer-assisted image subtraction of images of enzymatically digested tissue sections from those of adjacent control sections will be used to produce computer-generated difference pictures of the distribution of hyaluronate. We also plan to complete an algorithm for analysis of the amount of tannic acid precipitable material seen in electron micrographs. It will be used to assess the amount found in specific regions of the posterior palatal shelves of both normal and chlorcyclizine-treated embryos. A quantitative EM study of the epithelial-mesenchymal interface of morphogenetically active and inactive regions of the shelf perimeter of normal as compared to CHLOR-treated embryos during the course of shelf elevation will also be done. Finally, we plan to characterize these regions of the epithelial-mesenchymal interface at the EM level using resinless sections and specific enzymatic digestions.